Acts 19:18

‘Many also of those who had believed came, confessing, and declaring their deeds.'

It resulted in a widespread awareness of the seriousness of sin in God's eyes, and especially of being involved with the occult, and believers came and admitted to their secret sins. This suggests a period of true revival. In periods of true ‘revival', when the presence of God is experienced in a new way in the community, open confessions of sin become a regular feature as people seek to bring all out into the open for cleansing. Like Isaiah of old they have seen the Lord and they cry, ‘Woe is me, for I am undone' (Isaiah 6:5) because they are horrified at their sins as they see them in the light of God's presence (compare John 3:19). That is clearly what was happening here.